from what I've remembered in the novel, the silver-head guy is the only (presently) guide with high compatibility rate with the esper since he's an SS-Class and all of his "possible " guide got murdered 10 years ago by that silver-head guy.
Ohhh is that why that esper is like a slave to that guide?? He can just kill that guide and settle with low compatibility guidance that he can still survive instead being a slave to that psycho
the thing is in present timeline, there's no guide with a compatibility rate left for the Blond esper, the hyung mentioned that they're all killed 10 years ago. The silver-head guy made sure that he is the only guide left for him. He is so obsessed being with the strongest esper that he killed others. Now ML appears and his obsession shifted, the good thing here is that ML and MC has colossal mark that made it impossible to have other guide for ML unless the MC dies.
So, from all this hints, I believe the white haired guide killed the esper’s true guide and took his place. And it makes me so MAD because the esper knows this, hates him, but still craves him? Is he half esper, this guide? So he can force espers to need him? I don’t know, but I’m mad!